Gas mileage and general maintenance -- what else should I do...?

[sjconley]

Hello everyone!
I'm doing what I can to keep my truck (2007) on the road (it's soon-to-be 198k miles young) -- any recommendations are greatly appreciated. * Disclaimer: I'm NOT a mechanic, but I"m not afraid to get my hands dirty. *
My gas mileage has been crappier than usual for several months and I'm not sure why (it's running around 16 mpg -- should be 19-20 mpg). Last summer I changed the fuel rail pressure switch (along with the manifold intake gaskets and throttle body gasket), fuel filter, air filter, had the transmission serviced (flushed). More recently spark plugs & wires, serpentine belt & tensioner (today). What else should I add to my "to do" list? Any thoughts on how to improve the gas mileage??

P.S. Oil changes are done at the dealership (included with the vehicle purchase).

 

[Bill MacLeod]

Well, you certainly are taking care of basic maintenance. Good for you.

Stat and/or rad cap been changed lately? Possibly not running at proper operating temps?

What about brakes dragging?

I'm sure others will chime in.

 

[sjconley]

Thanks for the reply @Bill MacLeod -- I didn't respond back because I was hoping (as you mentioned), that others would chime in as well. I've not changed the radiator cap (never even thought of that) and I don't know what "stat" is...? I have read some older posts about changing the gas cap (in case it's leaking?) but I'm not sure how that concern would manifest (what symptoms?).
It's still not idling properly... of course I'm not sure how to explain it other than it just doesn't sound right. Gas mileage is a little over 17 mpg, still not great. I replaced the PCV valve just this past weekend, so I'll see if that makes any difference,
Right now I'm working on brakes and ball joints... a whole other set of issues (and questions).

 

[Mbrooks420]

A leaking gas cap would throw a CEL for an evaporative emissions leak.

Stat=thermostat.

 

[sjconley]

A leaking gas cap would throw a CEL for an evaporative emissions leak.

Stat=thermostat.

Thanks for the clarification -- I'll check that out as well.
I don't have a CEL (thankfully). Although my TPMS system isn't working so that light is always ON, and my airbag light has been ON lately (need to look into that also).